In sheet-fed printing machines and, in particular, sheet-fed offset printing machines of the type which is nowadays widespread, the drive is usually effected by means of one or more controlled drive motors onto a common, continuous train of gears which connects together the cylinders in the individual printing units and the transfer drums arranged between the printing units. In this case, a longitudinal shaft may additionally also be provided to reinforce this transmission train, by means of which shaft the driving output is introduced into the train of gears at several points via corresponding transmissions. Drive systems of this type are distinguished by their high printing quality, which is due to the highly synchronous functioning of the various printing units of the printing machine resulting from the rigid interconnection provided by the drive train. In this case, the required high rigidity in the train of driving gears serves, in particular, to avoid the so-called ghosting which occurs particularly when the rotational speed is changed.
A disadvantage in sheet-fed offset printing machines, in which the individual cylinders and the transfer drums arranged between the printing units are driven together with one another by means of a common train of gears, is that any automated operations to be completed outside the printing operation have to be carried out one after another. Sheet-fed offset printing machines, in particular, are increasingly being fitted with automatic washing devices for the blanket cylinders and/or the back pressure cylinders. It is also possible for washing devices to be provided for the rollers of the inking and/or damping unit. In order to achieve optimum washing results in each case on the different cylinders or rollers, in particular with the furthest possible reduction in the consumption and waste of detergent, individual control of the respective washing operations is required (e.g., number of revolutions and direction of rotation of the cylinders) during a washing operation (i.e., engagement and disengagement of the washing device to and from the cylinder to be cleaned). Individualized control operations, particularly in washing operations, therefore require the individual processes (e.g., the preparation of a new print order or during the execution of a print order), to be carried out one after another. The exchange of the printing plates for the preparation of a new print order should also be mentioned, since movements determined by the machine or the plate or form cylinders in the individual printing units in the sense of moving to predetermined positions have to be carried out as well as displacement by predetermined paths or angles.
In view of the foregoing, for the preparation of a new print order or while an existing print order is being carried out, a specific number of machine revolutions at correspondingly predetermined rotational speeds is always required in order to be able to carry out the required operations. Owing to the number of machine revolutions which in some cases cancel each other out or directions of rotation which may also cancel each other out in specific processes, the operations can consequently only be carried out one after another, so that in total a correspondingly high number of machine revolutions occurs and the time required to carry out the processes becomes correspondingly long.
Furthermore, the changes in format or the exchange of the printing material in the feeder and deliverer of the sheet-fed offset printing machine should also be mentioned. The feeder of a sheet-fed offset printing machine usually has a controllable clutch, by means of which the movement of the members bringing about the pickup of the sheets from the top of the pile and the conveying of the sheets to the feeder can be disengaged. Furthermore, a clutch arranged on the feeder drum is also known from DE 4 412 047 A1, by means of which both the said drum and the entire sheet conveying and delivery device arranged downstream of the drum can be disengaged. Although these previously known devices make it possible for the machine to continue rotating during a pile exchange in the feeder and deliverer (e.g. for a washing operation), this does not result in any further flexibility in terms of processes to be carried out simultaneously.
Similar to the prior art cited above, it is known from DE 4 102 472 A1 to individually drive the assemblies (i.e., feeder, printing units, deliverer) by means of separate. This previously known rotary printing machine avoids the effects of load fluctuations caused by the different assemblies, which effects leave a negative impression in the printing result.
A drive for a printing machine is known from DE 4 241 807 A1, in which a first drive is provided solely for all the cylinders serving to convey the printing material and for the plate cylinders, and drives the said cylinders by means of a continuous train of gears. Furthermore, at least one further drive is provided for the elements which do not serve to convey the printing material, each drive containing at least one motor, and transmitters for the movement parameters being provided, which are connected to a control and regulation device. In this case, this previously known drive arrangement is intended to help reduce the de-synchronizing influence exerted by the drive train of the elements that do not convey the printing material. Even in this type of device, however, the cylinders within the individual printing units and the cylinders or drums between them are connected together by means of a common train of gears. Thus, the disadvantages mentioned above remain in terms of the automated washing or the exchange of printing plates.
It is furthermore known in sheet-fed offset printing machines to design the plate or form cylinders to be remotely adjustable, to adjust the circumferential registration, in relation to the blanket cylinder which interacts with the plate or form cylinder. Devices for adjusting the circumferential registration, however, only permit small adjustments of the cylinder. With such devices, it is not possible to rotate the cylinder freely in relation to the gear wheel assigned to it. The same applies to the positioning motors which are assigned to the devices for adjusting the circumferential registration and can likewise only rotate the plate or form cylinder by predetermined distances or angular amounts. Coarse setting devices for the circumferential registration allow the plate or form cylinder to be released from the gear wheel assigned to it by manual loosening of screws and relatively large angular rotatation relative to the gear wheel. These devices are intended, in particular, to make possible large corrections in the circumferential registration or such corrections to overcome an incorrect plate copy with respect to the feed edge of a print. Adjusting devices of this type, however, require manual handling for the loosening and tightening of the connection, which is secured against rotation, between the driving gear wheel and the cylinder body. Furthermore, the adjustment of the cylinder by the appropriate distance or angular amount also has to be carried out by hand, using a special tool.